Blackjack

Provably fair

Verify fairness

The session's seed decides every card. Its hash was committed before the first hand; the seed is revealed when the session ends. Each round's cards come from HMAC-SHA256 keyed by the seed over the round's number and the bettor's own seed.

Seed hash

32494fada4e0f3312a258307c8f7e407e862e271305d9d3d2adf632cbae39d78

Seed

5e9fa00f924ebf9e83468287c6ecd322fcca8983accd3db51e7a17c41cd847d2 SHA-256 of "degen.match.seed.v1", a zero byte and the 32 seed bytes is the seed hash.

Bettor's seed

f0b35129b4e851d2a4f1a499e4c97896

Commitment

Batch 51,081, Merkle root fafb34adbb2f641f1ff442f5b4f68f21b4671e34a7fe08c7d2aee14a62613547. Recorded by Degen Protocol, not on a chain. See this batch and its Merkle tree

Merkle path

1. d89210d562cdb577c048f469fee04316170f47a0800d722175cafc69d2c0f7bd
2. 1e5828b256889f97b6d42152f0107e069478b8f2a15dbba809a324c3dbde009c
3. 605b7a717b7a1a4a78130ba26dc8e2c19158008366a177ad47ec1be67f531a64

Checked: the seed hash proves into the root.

To check it yourself, take the session's proof:

1. Hash the seed as above and compare it with the seed hash; prove the seed hash into the root with the Merkle path (keccak256, as for every match).
2. For each round: round seed = HMAC-SHA256(key = seed, "degen.house.round.v1" ‖ 0x00 ‖ u64be(length of the bettor's seed) ‖ bettor's seed ‖ u64be(round)).
3. Key ChaCha20 (RFC 8439, zero nonce) with the round seed and read little-endian 64-bit words; a card is the next word below 2⁶⁴ − 1 − ((2⁶⁴ − 1) mod 52), modulo 52.
4. Replay the round's actions with the game's rules: the cards and the payout must match.

The replay plays every hand rebuilt this way on the server from the same data, and marks any that does not rebuild as recorded.